Coke (fuel)

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Raw coke Koks Brennstoff.jpg
Raw coke

Coke is a grey, hard, and porous coal-based fuel with a high carbon content. It is made by heating coal or petroleum in the absence of air. Coke is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges.

Contents

The unqualified term "coke" usually refers to the product derived from low-ash and low-sulphur bituminous coal by a process called coking. A similar product called petroleum coke, or pet coke, is obtained from crude petroleum in petroleum refineries. Coke may also be formed naturally by geologic processes. [1] It is the residue of a destructive distillation process.

Production

Industrial coke furnaces

A coke oven at a smokeless fuel plant, Abercwmboi, South Wales, 1976 Coke Ovens Abercwmboi.jpg
A coke oven at a smokeless fuel plant, Abercwmboi, South Wales, 1976

The industrial production of coke from coal is called coking. The coal is baked in an airless kiln, a "coke furnace" or "coking oven", at temperatures as high as 2,000 °C (3,600 °F) but usually around 1,000–1,100 °C (1,800–2,000 °F). [2] This process vaporises or decomposes organic substances in the coal, driving off water and other volatile and liquid products such as coal gas and coal tar. Coke is the non-volatile residue of the decomposition, the cemented-together carbon and mineral residue of the original coal particles in the form of a hard and somewhat glassy solid.[ citation needed ]

Additional byproducts of the coking are coal tar pitch, ammonia (NH3), hydrogen sulphide (H2S), pyridine, hydrogen cyanide and carbon based material. [3] Some facilities have "by-product" coking ovens in which the volatile decomposition products are collected, purified and separated for use in other industries, as fuel or chemical feedstocks. Otherwise the volatile byproducts are burned to heat the coking ovens. This is an older method, but is still being used for new construction. [4]

Sources

Bituminous coal must meet a set of criteria for use as coking coal, determined by particular coal assay techniques. These include moisture content, ash content, sulphur content, volatile content, tar, and plasticity. The goal is to achieve a blend of coal that when processed will produce a coke of appropriate strength (generally measured by coke strength after reaction), while losing an appropriate amount of mass. Other blending considerations include ensuring the coke will not swell too much during production and destroy the coke oven through excessive wall pressures.

The greater the volatile matter in coal, the more by-product can be produced. It is generally considered that levels of 26–29% of volatile matter in the coal blend are good for coking purposes. Thus, different types of coal are proportionally blended to reach acceptable levels of volatility before the coking process begins. If the range of coal types is too great, the resulting coke is of widely varying strength and ash content, and is usually unsaleable, although in some cases it may be sold as an ordinary heating fuel. As coke has already lost its volatile matter, it cannot be coked again.

Coking coal is different from thermal coal, but arises from the same basic coal-forming process. Coking coal has different macerals from thermal coal, i.e. different forms of the compressed and fossilized vegetative matter that compose the coal. The different macerals arise from different mixtures of the plant species, and variations of the conditions under which the coal has formed. Coking coal is graded according to its ash percentage-by-weight after burning:

  • Steel Grade I (Ash content not exceeding 15%)
  • Steel Grade II (Exceeding 15% but not exceeding 18%)
  • Washery Grade I (Exceeding 18% but not exceeding 21%)
  • Washery Grade II (Exceeding 21% but not exceeding 24%)
  • Washery Grade III (Exceeding 24% but not exceeding 28%)
  • Washery Grade IV (Exceeding 28% but not exceeding 35%) [5]

The "hearth" process

The "hearth" process of coke-making, using lump coal, was akin to that of charcoal-burning; instead of a heap of prepared wood, covered with twigs, leaves and earth, there was a heap of coal, covered with coke dust. The hearth process continued to be used in many areas during the first half of the 19th century, but two events greatly lessened its importance. These were the invention of the hot blast in iron-smelting and the introduction of the beehive coke oven. The use of a blast of hot air, instead of cold air, in the smelting furnace was first introduced by Neilson in Scotland in 1828. [6] The hearth process of making coke from coal is a very lengthy process.[ citation needed ]

Beehive coke oven

Postcard depicting coke ovens and coal tipple in Pennsylvania Coke ovens and coal tipple, Fayette County, Penn (68762).jpg
Postcard depicting coke ovens and coal tipple in Pennsylvania

A fire brick chamber shaped like a dome is used, commonly known as a beehive oven. It is typically about 4 meters (13 ft) wide and 2.5 meters (8 ft) high. The roof has a hole for charging the coal or other kindling from the top. A discharging hole is provided in the circumference of the lower part of the wall. In a coke oven battery, a number of ovens are built in a row with common walls between neighboring ovens. A battery consisted of a great many ovens, sometimes hundreds, in a row. [7]

Coal is introduced from the top to produce an even layer of about 60 to 90 centimeters (24 to 35 in) deep. Air is supplied initially, to ignite the coal. Carbonization starts and produces volatile matter, which burns inside the partially closed side door. Carbonization proceeds from top to bottom and is completed in two to three days. The heat required for the process is supplied by the burning volatile matter, so no by-products are recovered. The exhaust gases are allowed to escape to the atmosphere. The hot coke is quenched with water, and is discharged manually through the side door. When the oven is used on a continuous basis, the walls and roof retain enough heat to initiate carbonization of the next charge.

When coal was burned in a coke oven, the impurities of the coal that were not driven off as gases accumulated in the oven as slag – effectively a conglomeration of the removed impurities. Since this slag was not the desired product, it was initially just discarded. Later, however, coke oven slag was found to be useful, and has since been used as an ingredient in brick-making, mixed cement, granule-covered shingles, and even as a fertilizer. [8]

Occupational safety

People can be exposed to coke oven emissions in the workplace by inhalation, skin contact, or eye contact. For the United States, the Occupational Safety and Health Administration (OSHA) has set the legal limit for coke oven emissions exposure in the workplace as 0.150 mg/m3 benzene-soluble fraction over an eight-hour workday. The US National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 0.2 mg/m3 benzene-soluble fraction over an eight-hour workday. [9]

Uses

Coke can be used as a fuel and as a reducing agent in smelting iron ore in a blast furnace. [10] The carbon monoxide produced by combustion of coke reduces iron oxide (hematite) to produce iron: [11]

.

Coke is commonly used as fuel for blacksmithing.

Coke was used in Australia in the 1960s and early 1970s for house heating,[ citation needed ] and was incentivized for home use in the UK (so as to displace coal) after the 1956 Clean Air Act, which was passed in response to the Great Smog of London in 1952.

Since smoke-producing constituents are driven off during the coking of coal, coke forms a desirable fuel for stoves and furnaces in which conditions are not suitable for the complete burning of bituminous coal itself. Coke may be combusted producing little or no smoke, while bituminous coal would produce much smoke. Coke was widely used as a smokeless fuel substitute for coal in domestic heating following the creation of "smokeless zones" in the United Kingdom.

Highland Park distillery in Orkney roasts malted barley for use in their Scotch whisky in kilns burning a mixture of coke and peat. [12]

Coke may be used to make synthesis gas, a mixture of carbon monoxide and hydrogen.

In foundry components

Finely ground bituminous coal, known in this application as sea coal, is a constituent of foundry sand. While the molten metal is in the mould, the coal burns slowly, releasing reducing gases at pressure, and so preventing the metal from penetrating the pores of the sand. It is also contained in 'mould wash', a paste or liquid with the same function applied to the mould before casting. [15] Sea coal can be mixed with the clay lining (the "bod") used for the bottom of a cupola furnace. When heated, the coal decomposes and the bod becomes slightly friable, easing the process of breaking open holes for tapping the molten metal. [16]

Phenolic byproducts

Wastewater from coking is highly toxic and carcinogenic. It contains phenolic, aromatic, heterocyclic, and polycyclic organics, and inorganics including cyanides, sulfides, ammonium and ammonia. [17] Various methods for its treatment have been studied in recent years. [18] [19] [20] The white rot fungus Phanerochaete chrysosporium can remove up to 80% of phenols from coking waste water. [21]

Properties

Hanna furnaces of the Great Lakes Steel Corporation, Detroit. Coal tower atop coke ovens. November 1942 Siegelfurnace1.jpg
Hanna furnaces of the Great Lakes Steel Corporation, Detroit. Coal tower atop coke ovens. November 1942

Before bituminous coal is used as coking coal, it must meet a set of criteria determined by particular coal assay techniques.

The bulk specific gravity of coke is typically around 0.77. It is highly porous. Both the chemical composition and physical properties are important to the usefulness of coke in blast furnaces. In terms of composition, low ash and sulphur content are desirable. Other important characteristics are the M10, M25, and M40 test crush indexes, which convey the strength of coke during transportation into the blast furnaces; depending on the blast furnace's size, finely crushed coke pieces must not be allowed into the furnace because they would impede the flow of gas through the charge of iron and coke. A related characteristic is the Coke Strength After Reaction (CSR) index; it represents coke's ability to withstand the violent conditions inside the blast furnace before turning into fine particles. Pieces of coke are denoted with the following terminology: "bell coke" (30 - 80 mm), "nut coke" (10 - 30 mm), "coke breeze" (< 10 mm). [22]

The water content in coke is practically zero at the end of the coking process, but it is often water quenched so that it can be transported to the blast furnaces. The porous structure of coke absorbs some water, usually 3–6% of its mass. In more modern coke plants an advanced method of coke cooling uses air quenching.

Other processes

The Illawarra Coke Company (ICC) in Coalcliff, New South Wales, Australia CoalcliffICC.jpg
The Illawarra Coke Company (ICC) in Coalcliff, New South Wales, Australia

The solid residue remaining from refinement of petroleum by the "cracking" process is also a form of coke. Petroleum coke has many uses besides being a fuel, such as the manufacture of dry cells and of electrolytic and welding electrodes.

Gas works manufacturing syngas also produce coke as an end product, called gas house coke.

Fluid coking is a process which converts heavy residual crude into lighter products such as naphtha, kerosene, heating oil, and hydrocarbon gases. The "fluid" term refers to the fact that solid coke particles behave as a fluid solid in the continuous fluid coking process versus the older batch delayed-coking process where a solid mass of coke builds up in the coke drum over time.

Due to a lack of oil or high-quality coals in East Germany, scientists developed a process to turn low-quality lignite into coke called high temperature lignite coke.

Alternatives to coke

Scrap steel can be recycled in an electric arc furnace; and an alternative to making iron by smelting is direct reduced iron, where any carbonaceous fuel can be used to make sponge or pelletised iron. To lessen carbon dioxide emissions hydrogen can be used as the reducing agent [23] and biomass or waste as the source of carbon. [24] Historically, charcoal has been used as an alternative to coke in a blast furnace, with the resultant iron being known as charcoal iron.

History

China

Many historical sources dating to the 4th century describe the production of coke in ancient China. [25] The Chinese first used coke for heating and cooking no later than the 9th century.[ citation needed ] By the first decades of the 11th century, Chinese ironworkers in the Yellow River valley began to fuel their furnaces with coke, solving their fuel problem in that tree-sparse region. [26] By 1078 CE, the implementation of coke as a replacement to charcoal in the production of iron in China dramatically increased the industry to 125,000 tons per year. The iron was used for the creation of tools, weapons, chains for suspension bridges, and Buddhist statues. [27]

China is the largest producer and exporter of coke today. [28] China produces 60% of the world's coke. Concerns about air pollution have motivated technological changes in the coke industry by elimination of outdated coking technologies that are not energy-efficient. [29]

Britain

In 1589, a patent was granted to Thomas Proctor and William Peterson for making iron and steel and melting lead with "earth-coal, sea-coal, turf, and peat". The patent contains a distinct allusion to the preparation of coal by "cooking". In 1590, a patent was granted to the Dean of York to "purify pit-coal and free it from its offensive smell". [30] In 1620, a patent was granted to a company composed of William St. John and other knights, mentioning the use of coke in smelting ores and manufacturing metals. In 1627, a patent was granted to Sir John Hacket and Octavius de Strada for a method of rendering sea-coal and pit-coal as useful as charcoal for burning in houses, without offense by smell of smoke. [31]

In 1603, Hugh Plat suggested that coal might be charred in a manner analogous to the way charcoal is produced from wood. This process was not employed until 1642, when coke was used for roasting malt in Derbyshire; previously, brewers had used wood, as uncoked coal cannot be used in brewing because its sulphurous fumes would impart a foul taste to the beer. [32] It was considered an improvement in quality, and brought about an "alteration which all England admired"—the coke process allowed for a lighter roast of the malt, leading to the creation of what by the end of the 17th century was called pale ale. [31]

The original blast furnaces at Blists Hill, Madeley Blast Furnaces at Blists Hill.jpg
The original blast furnaces at Blists Hill, Madeley

In 1709, Abraham Darby I established a coke-fired blast furnace to produce cast iron. Coke's superior crushing strength allowed blast furnaces to become taller and larger. The ensuing availability of inexpensive iron was one of the factors leading to the Industrial Revolution. Before this time, iron-making used large quantities of charcoal, produced by burning wood. As the coppicing of forests became unable to meet the demand, the substitution of coke for charcoal became common in Great Britain, and coke was manufactured by burning coal in heaps on the ground so that only the outer layer burned, leaving the interior of the pile in a carbonized state. In the late 18th century, brick beehive ovens were developed, which allowed more control over the burning process. [33]

In 1768, John Wilkinson built a more practical oven for converting coal into coke. [34] Wilkinson improved the process by building the coal heaps around a low central chimney built of loose bricks and with openings for the combustion gases to enter, resulting in a higher yield of better coke. With greater skill in the firing, covering and quenching of the heaps, yields were increased from about 33% to 65% by the middle of the 19th century. The Scottish iron industry expanded rapidly in the second quarter of the 19th century, through the adoption of the hot-blast process in its coalfields. [6]

In 1802, a battery of beehive ovens was set up near Sheffield, to coke the Silkstone coal seam for use in crucible steel melting. By 1870, there were 14,000 beehive ovens in operation on the West Durham coalfields, producing 4,000,000 long tons of coke per year. As a measure of the expansion of coke making, the requirements of the iron industry in Britain were about 1,000,000 tons per year in the early 1850s, rising to about 7,000,000 tons by 1880. Of these, about 5,000,000 tons were produced in Durham county, 1,000,000 tons in the South Wales coalfield, and 1,000,000 tons in Yorkshire and Derbyshire. [6]

41 018 of the Deutsche Reichsbahn climbing the famous Schiefe Ebene, 2016 41018 Schiefe Ebene Nov 5 2016.png
41 018 of the Deutsche Reichsbahn climbing the famous Schiefe Ebene, 2016

In the first years of steam locomotives, coke was the normal fuel. This resulted from an early piece of environmental legislation; any proposed locomotive had to "consume its own smoke". [35] This was not technically possible to achieve until the firebox arch came into use, but burning coke, with its low smoke emissions, was considered to meet the requirement. This rule was quietly dropped, and cheaper coal became the normal fuel, as railways gained acceptance among the public. The smoke plume produced by a travelling locomotive seems now to be a mark of a steam railway, and so preserved for posterity.

So-called "gas works" produced coke by heating coal in enclosed chambers. The flammable gas that was given off was stored in gas holders, to be used domestically and industrially for cooking, heating and lighting. The gas was commonly known as "town gas" since underground networks of pipes ran through most towns. It was replaced by "natural gas" (initially from the North Sea oil and gas fields) in the decade after 1967.[ citation needed ] Other byproducts of coke production included tar and ammonia, while the coke was used instead of coal in cooking ranges and to provide heat in domestic premises before the advent of central heating.

United States

Illustration of coal mining and coke burning from 1879 Coke burning.jpg
Illustration of coal mining and coke burning from 1879

In the US, the first use of coke in an iron furnace occurred around 1817 at Isaac Meason's Plumsock puddling furnace and rolling mill in Fayette County, Pennsylvania. [36] In the late 19th century, the coalfields of western Pennsylvania provided a rich source of raw material for coking. In 1885, the Rochester and Pittsburgh Coal and Iron Company [37] constructed the world's longest string of coke ovens in Walston, Pennsylvania, with 475 ovens over a length of 2 km (1.25 miles). Their output reached 22,000 tons per month. The Minersville Coke Ovens in Huntingdon County, Pennsylvania, were listed on the National Register of Historic Places in 1991. [38]

Between 1870 and 1905, the number of beehive ovens in the US increased from approximately 200 to nearly 31,000, which produced nearly 18,000,000 tons of coke in the Pittsburgh area alone. [39] One observer boasted that if loaded into a train, "the year's production would make up a train so long that the engine in front of it would go to San Francisco and come back to Connellsville before the caboose had gotten started out of the Connellsville yards!" The number of beehive ovens in Pittsburgh peaked in 1910 at almost 48,000. [40]

Although it made a top-quality fuel, coking poisoned the surrounding landscape. After 1900, the serious environmental damage of beehive coking attracted national notice, although the damage had plagued the district for decades. "The smoke and gas from some ovens destroy all vegetation around the small mining communities", noted W. J. Lauck of the U.S. Immigration Commission in 1911. [41] Passing through the region on train, University of Wisconsin president Charles Van Hise saw "long rows of beehive ovens from which flame is bursting and dense clouds of smoke issuing, making the sky dark. By night, the scene is rendered indescribably vivid by these numerous burning pits. The beehive ovens make the entire region of coke manufacture one of dulled sky: cheerless and unhealthful." [41]

See also

Related Research Articles

<span class="mw-page-title-main">Coal</span> Combustible sedimentary rock composed primarily of carbon

Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is a type of fossil fuel, formed when dead plant matter decays into peat which is converted into coal by the heat and pressure of deep burial over millions of years. Vast deposits of coal originate in former wetlands called coal forests that covered much of the Earth's tropical land areas during the late Carboniferous (Pennsylvanian) and Permian times.

<span class="mw-page-title-main">Forge</span> Workshops of blacksmith, who is an ironsmith who makes iron into tools or other objects

A forge is a type of hearth used for heating metals, or the workplace (smithy) where such a hearth is located. The forge is used by the smith to heat a piece of metal to a temperature at which it becomes easier to shape by forging, or to the point at which work hardening no longer occurs. The metal is transported to and from the forge using tongs, which are also used to hold the workpiece on the smithy's anvil while the smith works it with a hammer. Sometimes, such as when hardening steel or cooling the work so that it may be handled with bare hands, the workpiece is transported to the slack tub, which rapidly cools the workpiece in a large body of water. However, depending on the metal type, it may require an oil quench or a salt brine instead; many metals require more than plain water hardening. The slack tub also provides water to control the fire in the forge.

<span class="mw-page-title-main">Bituminous coal</span> Collective term for higher-quality coal

Bituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the seams. It is typically hard but friable. Its quality is ranked higher than lignite and sub-bituminous coal, but lesser than anthracite. It is the most abundant rank of coal, with deposits found around the world, often in rocks of Carboniferous age. Bituminous coal is formed from sub-bituminous coal that is buried deeply enough to be heated to 85 °C (185 °F) or higher.

<span class="mw-page-title-main">Anthracite</span> Hard, compact variety of coal

Anthracite, also known as hard coal and black coal, is a hard, compact variety of coal that has a submetallic lustre. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coals.

<span class="mw-page-title-main">Steelmaking</span> Process for producing steel from iron ore and scrap

Steelmaking is the process of producing steel from iron ore and/or scrap. In steelmaking, impurities such as nitrogen, silicon, phosphorus, sulfur, and excess carbon are removed from the sourced iron, and alloying elements such as manganese, nickel, chromium, carbon, and vanadium are added to produce different grades of steel.

<span class="mw-page-title-main">Pyrolysis</span> Thermal decomposition of materials

Pyrolysis is the process of thermal decomposition of materials at elevated temperatures, often in an inert atmosphere without access to oxygen.

<span class="mw-page-title-main">Blast furnace</span> Type of furnace used for smelting to produce industrial metals

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being supplied above atmospheric pressure.

Coal gas is a flammable gaseous fuel made from coal and supplied to the user via a piped distribution system. It is produced when coal is heated strongly in the absence of air. Town gas is a more general term referring to manufactured gaseous fuels produced for sale to consumers and municipalities.

<span class="mw-page-title-main">Solid fuel</span> Solid material that can be burnt to release energy

Solid fuel refers to various forms of solid material that can be burnt to release energy, providing heat and light through the process of combustion. Solid fuels can be contrasted with liquid fuels and gaseous fuels. Common examples of solid fuels include wood, charcoal, peat, coal, hexamine fuel tablets, dry dung, wood pellets, corn, wheat, rice, rye, and other grains. Solid fuels are extensively used in rocketry as solid propellants. Solid fuels have been used throughout human history to create fire and solid fuel is still in widespread use throughout the world in the present day.

<span class="mw-page-title-main">Dry distillation</span> Heating of solids to produce gases

Dry distillation is the heating of solid materials to produce gaseous products. The method may involve pyrolysis or thermolysis, or it may not.

Anthracite iron or anthracite pig iron is iron extracted by the smelting together of anthracite coal and iron ore, that is using anthracite coal instead of charcoal in iron smelting. This was an important technical advance in the late-1830s, enabling a great acceleration of the Industrial Revolution in the United States and in Europe.

<span class="mw-page-title-main">Reverberatory furnace</span> Metallurgical furnace

A reverberatory furnace is a metallurgical or process furnace that isolates the material being processed from contact with the fuel, but not from contact with combustion gases. The term reverberation is used here in a generic sense of rebounding or reflecting, not in the acoustic sense of echoing.

<span class="mw-page-title-main">Petroleum coke</span> Solid carbon-rich material

Petroleum coke, abbreviated coke, pet coke or petcoke, is a final carbon-rich solid material that derives from oil refining, and is one type of the group of fuels referred to as cokes. Petcoke is the coke that, in particular, derives from a final cracking process—a thermo-based chemical engineering process that splits long chain hydrocarbons of petroleum into shorter chains—that takes place in units termed coker units. Stated succinctly, coke is the "carbonization product of high-boiling hydrocarbon fractions obtained in petroleum processing ". Petcoke is also produced in the production of synthetic crude oil (syncrude) from bitumen extracted from Canada's tar sands and from Venezuela's Orinoco oil sands. In petroleum coker units, residual oils from other distillation processes used in petroleum refining are treated at a high temperature and pressure leaving the petcoke after driving off gases and volatiles, and separating off remaining light and heavy oils. These processes are termed "coking processes", and most typically employ chemical engineering plant operations for the specific process of delayed coking.

Coking is the process of heating coal in the absence of oxygen to a temperature above 600 °C (1,112 °F) to drive off the volatile components of the raw coal, leaving behind a hard, strong, porous material with a high carbon content called coke. Coke is predominantly carbon. Its porous structure provides a high surface area, allowing it to burn more rapidly, much like how a bundle of tinder burns faster than a solid wooden log. As such, when a kilogram of coke is burned, it releases more heat than a kilogram of the original coal.

<span class="mw-page-title-main">Blast furnace gas</span> Gas mixture as by-product of steelworks

Blast furnace gas (BFG) is a by-product of blast furnaces that is generated when the iron ore is reduced with coke to metallic iron. It has a very low heating value, about 3.5 MJ/m3 (93 BTU/cu.ft), because it consists of about 51 vol% nitrogen and 22 vol% carbon dioxide, which are not flammable. The rest amounts to around 22 vol% carbon monoxide, which has a fairly low heating value already and 5 vol% hydrogen. Per ton of steel produced via the blast furnace route, 2.5 to 3.5 tons of blast furnace gas is produced. It is commonly used as a fuel within the steel works, but it can be used in boilers and power plants equipped to burn it. It may be combined with natural gas or coke oven gas before combustion or a flame support with richer gas or oil is provided to sustain combustion. Particulate matter is removed so that it can be burned more cleanly. Blast furnace gas is sometimes flared without generating heat or electricity.

<span class="mw-page-title-main">Hot blast</span> Metallurgical preheating of air

Hot blast refers to the preheating of air blown into a blast furnace or other metallurgical process. As this considerably reduced the fuel consumed, hot blast was one of the most important technologies developed during the Industrial Revolution. Hot blast also allowed higher furnace temperatures, which increased the capacity of furnaces.

<span class="mw-page-title-main">Beehive oven</span> Type of oven


A beehive oven is a type of oven in use since the Middle Ages in Europe. It gets its name from its domed shape, which resembles that of a skep, an old-fashioned type of beehive.

<span class="mw-page-title-main">Smokeless fuel</span>

Smokeless fuel is a type of solid fuel which either does not emit visible smoke or emits minimal amounts during combustion. These types of fuel find use where the use of fuels which produce smoke, such as coal and unseasoned or wet wood, is prohibited.

<span class="mw-page-title-main">Charcoal</span> Lightweight black carbon residue

Charcoal is a lightweight black carbon residue produced by strongly heating wood in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, often by forming a charcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen. The material can also be heated in a closed retort. Modern charcoal briquettes used for outdoor cooking may contain many other additives, e.g. coal.

<span class="mw-page-title-main">Coking factory</span> Type of factory

A coking factory or a coking plant is where coke and manufactured gas are synthesized from coal using a dry distillation process. The volatile components of the pyrolyzed coal, released by heating to a temperature of between 900°C and 1,400 °C, are generally drawn off and recovered. There are also coking plants where the released components are burned: this is known as a heat recovery process. A layer of ash then forms on the surface of the resulting coke. The degassing of the coal gives the coke a highly sought-after porosity. The gases are broken down by fractional condensation into hydrocarbon tars, sulfuric acid, ammonia, naphthalene, benzol, and coke gas; these products are then purified in further chemical reactors. Germany still has five coking plants in operation to meet the needs of its domestic industry.

References

  1. ↑ B. Kwiecińska and H. I. Petersen (2004): "Graphite, semi-graphite, natural coke, and natural char classification — ICCP system". International Journal of Coal Geology, volume 57, issue 2, pages 99-116. doi : 10.1016/j.coal.2003.09.003
  2. ↑ "Coal and Steel". World Coal Association. 28 April 2015. Archived from the original on 14 March 2012.
  3. ↑ Tiwari, H. P.; Sharma, R.; Kumar, Rajesh; Mishra, Prakhar; Roy, Abhijit; Haldar, S. K. (December 2014). "A review of coke making by-products". Coke and Chemistry. 57 (12): 477–484. doi:10.3103/S1068364X14120072. ISSN   1068-364X. S2CID   98805474.
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  5. ↑ "Coal Grades". Ministry of Coal. Archived from the original on 1 February 2016.
  6. 1 2 3 Beaver, S. H. (1951). "Coke Manufacture in Great Britain: A Study in Industrial Geography". Transactions and Papers (Institute of British Geographers). The Royal Geographical Society (with the Institute of British Geographers (17): 133–48. doi:10.2307/621295. JSTOR   621295.
  7. ↑ "Manufacture of Coke at Salem No. 1 Mine Coke Works". Pathoftheoldminer. Archived from the original on 3 July 2013. Retrieved 14 May 2013.
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  10. ↑ Chisholm, Hugh, ed. (1911). "Coke"  . Encyclopædia Britannica . Vol. 6 (11th ed.). Cambridge University Press. p. 657.
  11. ↑ "Science Aid: Blast Furnace" . Retrieved 13 October 2021.
  12. ↑ The Scotch Malt Whisky Society: Highland Park: Where the peat still reeks in the old way "The Scotch Malt Whisky Society - USA". Archived from the original on 16 July 2011. Retrieved 22 February 2011.
  13. ↑ "Different Gases from Steel Production Processes" . Retrieved 5 July 2020.
  14. ↑ "Steel making today and tomorrow" . Retrieved 30 June 2019.
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  27. ↑ Ebrey, Patricia B (2010). "Shifting South: The Song Dynasty". Cambridge Illustrated History of China (2nd ed.). Cambridge: Cambridge University Press. pp. 143–144. ISBN   978-0521435192.
  28. ↑ He, Q., Yan, Y., Zhang, Y. et al. Coke workers’ exposure to volatile organic compounds in northern China: a case study in Shanxi Province. Environ Monit Assess 187, 359 (2015). doi : 10.1007/s10661-015-4582-7
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  31. 1 2 Peckham, Stephen (1880). Special Reports on Petroleum, Coke, and Building Stones. United States Census Office. 10th census. p. 53.
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  35. ↑ Railways Clauses Consolidation Act 1845 (8 & 9 Vict. c. 20) section 114
  36. ↑ DiCiccio, Carmen. Coal and Coke in Pennsylvania. Harrisburg, PA: Pennsylvania Historical and Museum Commission.
  37. ↑ A subsidiary of the Buffalo, Rochester and Pittsburgh Railway.
  38. ↑ "National Register Information System". National Register of Historic Places . National Park Service. 9 July 2010.
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  40. ↑ Warren, Kenneth (2001). Wealth, Waste, and Alienation: Growth and Decline in the Connellsville Coke Industry. Pittsburgh, PA: University of Pittsburgh.
  41. 1 2 Martin, Scott C. Killing Time: Leisure and Culture in Southwestern Pennsylvania, 1800–1850. Pittsburgh, PA: University of Pittsburgh Press.
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